Integration of morphogen signalling within the growth regulatory network.

The need to coordinate patterning and growth has been appreciated for many years. The logic that enables seamless integration of the relevant inputs is beginning to be elucidated, particularly in wing imaginal discs of Drosophila. In this tissue, multiple regulatory layers involving the two morphogens Wingless and Dpp, the wing-specific determinant, Vestigial, and the Hippo pathway, converge to regulate growth. Intricate cross-regulation between these components may explain why, at the local level, there is no direct correlation between growth and the graded signalling activity of Wingless and Dpp, despite the requirement of these two pathways for growth.